1 files changed, 66 insertions, 0 deletions
diff --git a/spec/ruby/core/hash/dig_spec.rb b/spec/ruby/core/hash/dig_spec.rb
new file mode 100644
index 0000000000..94ac94e850
--- /dev/null
+++ b/spec/ruby/core/hash/dig_spec.rb
@@ -0,0 +1,66 @@
+require_relative '../../spec_helper'
+
+describe "Hash#dig" do
+
+  it "returns #[] with one arg" do
+    h = { 0 => false, a: 1 }
+    h.dig(:a).should == 1
+    h.dig(0).should == false
+    h.dig(1).should == nil
+  end
+
+  it "returns the nested value specified by the sequence of keys" do
+    h = { foo: { bar: { baz: 1 } } }
+    h.dig(:foo, :bar, :baz).should == 1
+    h.dig(:foo, :bar, :nope).should == nil
+    h.dig(:foo, :baz).should == nil
+    h.dig(:bar, :baz, :foo).should == nil
+  end
+
+  it "returns the nested value specified if the sequence includes an index" do
+    h = { foo: [1, 2, 3] }
+    h.dig(:foo, 2).should == 3
+  end
+
+  it "returns nil if any intermediate step is nil" do
+    h = { foo: { bar: { baz: 1 } } }
+    h.dig(:foo, :zot, :xyz).should == nil
+  end
+
+  it "raises an ArgumentError if no arguments provided" do
+    -> { { the: 'borg' }.dig() }.should.raise(ArgumentError)
+  end
+
+  it "handles type-mixed deep digging" do
+    h = {}
+    h[:foo] = [ { bar: [ 1 ] }, [ obj = Object.new, 'str' ] ]
+    def obj.dig(*args); [ 42 ] end
+
+    h.dig(:foo, 0, :bar).should == [ 1 ]
+    h.dig(:foo, 0, :bar, 0).should == 1
+    h.dig(:foo, 1, 1).should == 'str'
+    # MRI does not recurse values returned from `obj.dig`
+    h.dig(:foo, 1, 0, 0).should == [ 42 ]
+    h.dig(:foo, 1, 0, 0, 10).should == [ 42 ]
+  end
+
+  it "raises TypeError if an intermediate element does not respond to #dig" do
+    h = {}
+    h[:foo] = [ { bar: [ 1 ] }, [ nil, 'str' ] ]
+    -> { h.dig(:foo, 0, :bar, 0, 0) }.should.raise(TypeError)
+    -> { h.dig(:foo, 1, 1, 0) }.should.raise(TypeError)
+  end
+
+  it "calls #dig on the result of #[] with the remaining arguments" do
+    h = { foo: { bar: { baz: 42 } } }
+    h[:foo].should_receive(:dig).with(:bar, :baz).and_return(42)
+    h.dig(:foo, :bar, :baz).should == 42
+  end
+
+  it "respects Hash's default" do
+    default = {bar: 42}
+    h = Hash.new(default)
+    h.dig(:foo).should.equal? default
+    h.dig(:foo, :bar).should == 42
+  end
+end